The present invention relates to ion generation.
The term xe2x80x9cefficiencyxe2x80x9d as used herein, relates to the proportion of ions exiting a device for ion generation, relative to the total volume produced. The efficiency is also referred to herein as may the coefficient of ion exit.
It is known that besides ions, neutral ozone molecules are simultaneously produced in the field of a corona discharge.
In prior art methods and devices for ion generation, ions are removed from the corona system by means of an air flow from a fan or a compressor. Accordingly, the ion flow direction to the generator exit coincides with that of the air flow.
Due to the great difference between the speed of the air flow and that of the ions in the field of a corona discharge, a significant part of the ion stream remains inside the system. Thus by the known method and known devices, the coefficient of ion removal from the generator the ratio of the ions quantity at the output of the generator to the number of ions produced by the generator remains rather low.
At the same time together with ions the whole amount of ozone produced in the corona system is also removed by the air flow.
An indication of the state of the art is provided by the following patent publications: PCT application no. WO95/19225, entitled Air Cleaning Apparatus, and U.S. Pat. No. 5,055,963, entitled Self-Balancing Bipolar Air Ionizer, employ fans. In WO95/19225, a fan is provided so as to produce an inflow of air to be cleaned. In U.S. Pat. No. 5,055,963, a fan xe2x80x9cdraws air into the housing through the inlet passage and directs air out of the housing . . . xe2x80x9d for promoting xe2x80x9cintermixing of . . . positive and negative ions as the air flow travels through the outlet passagexe2x80x9d column 3, lines 4-9.
The present invention seeks to provide a method and device for generating ions which are characterized by an efficiency which is substantially greater than in the known art.
The present invention further seeks to provide a method and device for substantially reducing the emission of ozone from the device, the generation of which accompanies corona discharge generation of ozone.
There is thus provided, in accordance with a preferred embodiment of the invention, a method of high efficiency generation of ions of desired polarity, which includes the steps of positioning a first electrode at a predetermined spacing from a second electrode having a closed shape configuration, applying to both electrodes a direct voltage of the same polarity, at the same time as applying the direct voltage, applying high voltage pulses across the first electrode only, thereby to cause ion generation in the vicinity of the first electrode and to set up a rapidly moving ion stream from the first to the second electrode along an electrical field therebetween, wherein the duration of the pulses is shorter than the time taken for the ion stream to reach the second electrode, and wherein ions in the ion stream have the same polarity as the second electrode, thereby to be repelled and concentrated as they flow through the second electrode.
Additionally in accordance with a preferred embodiment of the present invention, the coefficient of ion removal is regulated by changing the magnitude of direct voltage supplied to the electrodes.
In accordance with an alternative embodiment of the invention, there is also provided a device for performance of the above method.
In accordance with an additional embodiment of the invention, there is provided a method for the generation of a stream of ions, with reduced ozone content, which includes positioning a first electrode opposite a second electrode and applying predetermined electrical charges across the first and second electrodes so as to generate an ion stream by corona discharge; and applying a negative pressure gradient to the ion stream, thereby to deflect ozone generated by the corona discharge to a direction different from that of the flow of ions.
There is also provided a device for implementing this method.